In (REF ) the sample mean is computed
on \(2N_{b}\)  blocks overlapping by 50%, as suggested by the Welch's
estimator of the power spectrum of a random process [1]}.
Using (REF ) instead of (REF )
does not change the results of the estimate or the convergence region,
but gives smaller statistical errors where they can be computed. In
the following we keep the simpler notation (REF )
for ease of presentation.
